Numerical study of ionic contribution to susceptibility and impedance of dielectric liquid layer

The ionic contribution to the dielectric susceptibility and to the impedance of a thin layer of dielectric liquid subjected to ac electric field was studied numerically. Quasi-blocking electrodes and equal mobility of anions and cations were assumed. Field dependent dissociation and recombination were taken into account. The polarization resulting from the ionic space charge was calculated. Its non-sinusoidal time dependence revealed the non-linear properties of the system. The linear and non-linear components of dielectric susceptibility were calculated as functions of frequency. The influence of the amplitude of bias voltage, layer thickness, concentration and mobility of ions was also studied. The frequency dependence of the real and imaginary parts of the electrical impedance revealed features characteristic for an equivalent circuit formed by the series of two parallels of a resistance and a capacitance. One of them may be attributed to the electrodes and the other to the bulk of the layer.